47 lines
1.5 KiB
Diff
47 lines
1.5 KiB
Diff
From: Gerd Hoffmann <kraxel@redhat.com>
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Date: Wed, 8 Feb 2017 11:18:36 +0100
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Subject: [PATCH] cirrus: add blit_is_unsafe call to cirrus_bitblt_cputovideo
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(CVE-2017-2620)
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CIRRUS_BLTMODE_MEMSYSSRC blits do NOT check blit destination
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and blit width, at all. Oops. Fix it.
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Security impact: high.
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The missing blit destination check allows to write to host memory.
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Basically same as CVE-2014-8106 for the other blit variants.
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Cc: qemu-stable@nongnu.org
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Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
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(cherry picked from commit 92f2b88cea48c6aeba8de568a45f2ed958f3c298)
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---
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hw/display/cirrus_vga.c | 8 ++++++++
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1 file changed, 8 insertions(+)
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diff --git a/hw/display/cirrus_vga.c b/hw/display/cirrus_vga.c
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index 0e47cf85ad..a093dc8b16 100644
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--- a/hw/display/cirrus_vga.c
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+++ b/hw/display/cirrus_vga.c
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@@ -899,6 +899,10 @@ static int cirrus_bitblt_cputovideo(CirrusVGAState * s)
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{
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int w;
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+ if (blit_is_unsafe(s, true)) {
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+ return 0;
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+ }
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+
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s->cirrus_blt_mode &= ~CIRRUS_BLTMODE_MEMSYSSRC;
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s->cirrus_srcptr = &s->cirrus_bltbuf[0];
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s->cirrus_srcptr_end = &s->cirrus_bltbuf[0];
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@@ -924,6 +928,10 @@ static int cirrus_bitblt_cputovideo(CirrusVGAState * s)
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}
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s->cirrus_srccounter = s->cirrus_blt_srcpitch * s->cirrus_blt_height;
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}
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+
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+ /* the blit_is_unsafe call above should catch this */
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+ assert(s->cirrus_blt_srcpitch <= CIRRUS_BLTBUFSIZE);
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+
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s->cirrus_srcptr = s->cirrus_bltbuf;
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s->cirrus_srcptr_end = s->cirrus_bltbuf + s->cirrus_blt_srcpitch;
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cirrus_update_memory_access(s);
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